Thin battery

ABSTRACT

A thin battery includes a battery module ( 2 ) and an outer case ( 1 ) for housing the battery module ( 2 ), wherein a first case body ( 1 A) and a second case body ( 1 B) include connection walls ( 8 ), ( 18 ) for connecting the first case body ( 1 A) and the second case body ( 1 B) to each other on outer circumferential portions, at least one of the first case body ( 1 A) and the second case body ( 1 B) includes a dish-shaped case element ( 5 ) with a housing portion ( 7 ) swelling from one surface and a reinforcing frame ( 6 ) fixed to the case element ( 5 ) along a circumference of a swelling wall ( 11 ) of the housing portion ( 7 ), and the battery module ( 2 ) is housed in the housing portion ( 7 ), whereby a light-weight and small thin battery can be provided, which has sufficient structural strength while the total thickness of the battery is minimized.

TECHNICAL FIELD

The present invention relates to a card-shaped thin battery used, forexample, as a power source of a portable information terminal.

BACKGROUND ART

The above-mentioned type of battery is known in, for example,JP11(1999)-176400A. In this publication, as shown in FIG. 9, the batteryis composed of a battery unit 30, an outer case 31 for housing thebattery unit 30, a corrosion-preventive resin sheet 32 for separatingthe battery unit 30 from the outer case 31, and the like. The batteryunit 30 is formed in a flat mat shape with a winding body 33 compressedin an elliptical shape in cross-section, which includes a positiveelectrode, a negative electrode and a separator, an electrolytesolution, and a container 34 made of a laminated film for housing thewinding body 33 and the electrolyte solution. The outer case 31 iscomposed of an upper case 31 a and a lower case 31 b connected in alid-fitting manner. The battery unit 30 is sealed in the upper and lowercases 31 a and 31 b. The upper and lower cases 31 a and 31 brespectively are composed of a plate-shaped case wall member 35 obtainedby press-forming an aluminum plate material and plastic frames 36 fixedto front and back sides of four circumferential portions of the casewall member 35. For example, the case wall member 35 is subjected toinsert molding so as to be integrated with the frames 36 duringformation of the frames 36. There also is a battery obtained bysubjecting the upper and lower cases to plastics molding in theirentirety.

In the above-mentioned battery, the upper and lower cases 31 a and 31 bare composed of the case wall member 35 made of aluminum and the frames36 made of plastic. Therefore, the battery can be rendered light-weight.However, since the thick frames 36 are fixed to front and back sides offour circumferential portions of the case wall member 35, the totalthickness of the battery cannot help being enlarged, and there is alimit to the reduction in thickness of the battery.

Furthermore, according to the configuration in which the winding body 33including a positive electrode, a negative electrode, an electrolytesolution, and the like is sealed in the container 34 made of a laminatedfilm to obtain the battery unit 30, and the battery unit 30 is housed inthe outer case 31 provided separately from the battery unit 30, thenumber of components in the entire battery increases, and the productioncost of the battery also increases accordingly.

For example, as in a high-energy battery such as a lithium ion battery,a protection circuit for preventing overcharging and overdischarging andfurther preventing a large current from flowing is added, depending uponthe kind of the battery, so as to prepare for unexpected situations. Inthe above-mentioned card-shaped battery, it is necessary to separatelyprovide a space and an attachment base for setting a protection circuit,which increases the outer shape of the battery accordingly, or involvesmore labor for incorporating the protection circuit. In this regard, ina conventional battery in which an outer case is formed of a deep-drawncan, the protection circuit cannot help being housed in the outer case,so that a great amount of labor is required for electrical wiring andassembly.

DISCLOSURE OF INVENTION

The present invention relates to a thin battery comprising a batterymodule and an outer case for housing the battery module. The outer caseincludes a first case body and a second case body. The first case bodyand the second case body include connection walls for connecting thefirst case body and the second case body to each other on outercircumferential portions. At least one selected from the first case bodyand the second case body includes a dish-shaped case element with ahousing portion swelling from one surface and a reinforcing frame fixedto the case element along a circumference of a swelling wall of thehousing portion. The battery module is housed in the housing portion,and the battery module is sealed in the outer case by attaching theconnection wall of the first case body to the connection wall of thesecond case body.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view taken along a line A—A in FIG. 2.

FIG. 2 is a partially cutaway front view showing an example of a thinbattery of the present invention.

FIG. 3 is an exploded perspective view showing the example of the thinbattery of the present invention.

FIG. 4 is an exploded perspective view showing an example of a firstcase body.

FIG. 5 is a front view showing main portions in a state where examplesof a control module and a cover are disassembled.

FIG. 6 is a cross-sectional view taken along a line B—B in FIG. 2.

FIG. 7 is a cross-sectional view taken along a line C—C in FIG. 2.

FIG. 8 is a cross-sectional view showing main portions of anotherexample of the thin battery of the present invention.

FIG. 9 is an exploded cross-sectional view of a thin battery in aconventional example.

FIG. 10 is an external perspective view showing still another example ofthe thin battery of the present invention.

FIG. 11 is a perspective view showing main portions before the thinbattery shown in FIG. 10 is inserted in an apparatus.

FIG. 12 is a cross-sectional view in a state where the thin battery inshown in FIG. 10 is inserted in the apparatus.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention provide a thin battery that hassufficient structural strength while the total thickness of the batteryis minimized, and that is preferable as a power source of smallelectronic equipment strictly required to be light-weight andminiaturized, such as a portable information terminal and the like.

Furthermore, embodiments of the present invention provide a thin batteryin which an outer case is allowed to function as a housing container ofa battery module, whereby the number of components of the battery isreduced, and the production cost of the battery can be reducedaccordingly.

Furthermore, embodiments of the present invention provide a thin batteryin which the thickness of a card-shaped thin battery is not required toincrease and a control circuit such as a protection circuit can beassembled with respect to an outer case easily and exactly, and which isadvantageous for miniaturizing the entire battery provided with thecontrol circuit.

Hereinafter, an embodiment of the present invention will be describedwith reference to the drawings.

As shown in FIG. 3, an example of a thin battery in accordance with anembodiment of the present invention includes a battery module 2 and anouter case 1 for housing the battery module 2. The outer case 1 iscomposed of a first case body 1A and a second case body 1B of whichouter circumferential edges are connected to each other. As shown inFIG. 4, at least one of the first and second case bodies 1A and 1B iscomposed of a dish-shaped case element 5 in which a housing portion 7swells from one surface, and a reinforcing frame 6 fixed to the caseelement 5 along the circumference of a swelling wall 11 of the housingportion 7. Furthermore, as shown in FIG. 1, the battery module 2 housedin the housing portion 7 is sealed in the outer case 1 by attachingconnection walls 8 and 18, provided on circumferential edges of thefirst and second case bodies 1A and 1B, to each other.

More specifically, the reinforcing frame 6 is a plastic molding, thecase element 5 is a press-formed product made of a metal thin plate, andthe case element 5 is inserted into a mold during molding of thereinforcing frame 6 to be integrated with the reinforcing frame 6.

On an outer surface of the connection walls 8, 18 of the first case body1A and the second case body 1B, adjacent to the swelling wall 11 of thehousing portion 7, a mounting region Z is kept, as shown in FIG. 2, anda control module 3 for the battery module 2 and a cover 4 for protectingthe control module 3 are provided in the mounting region Z.

The control module 3 includes a protection circuit, a positive outputterminal, and a negative output terminal. As shown in FIG. 7, a pair ofinput terminals 21 p and 21 m of the control module 3 are connected tobe fixed to a positive tab 2 p and a negative tab 2 m of the batterymodule 2 led to the mounting region Z, whereby the control module 3 canbe fixed to the mounting region Z.

The mounting region Z is provided on one side of the outer case 1 formedin a rectangular card shape. As shown in FIG. 2, the cover 4 is composedof a principal plane wall 23 covering the outer surface of the controlmodule 3, and a pair of leg chips 24 projecting from both side ends ofthe principal plane wall 23, and terminal windows 25 for exposing outputterminals 20 of the control module 3 are opened on the principal planewall 23.

The outer case 1 of the present embodiment is composed of the first casebody 1A and the second case body 1B, and the battery module 2 is sealedin the housing portion 7 provided between the case bodies 1A and 1B.That is, the outer case 1 also functions as a housing container of thebattery module 2 to minimize the total thickness of the battery andreduce the number of components of the battery. Thus, according to thepresent invention, a thinner and lighter battery is obtained, and theproduction cost of the battery can be reduced by a decreased number ofcomponents.

When the case element 5 of at least one of the first and second casebodies 1A and 1B is reinforced with the reinforcing frame 6, thereinforcing frame 6 is placed around the swelling wall 11 of the housingportion 7 to reinforce the case element 5. Therefore, while thethickness of the battery is prevented from being increased, thestructural strength of the battery can be enhanced sufficiently. Thus,in spite of thinness, a battery strong to bending stress and drop impactcan be obtained. That is, a thin battery preferable as a power source ofsmall electronic equipment such as a portable information terminal orthe like, which is strictly required to be light-weight andminiaturized, can be obtained.

When the previously press-formed case element 5 is inserted into a moldduring molding of the reinforcing frame 6 to be integrated with thereinforcing frame 6, the number of processing of the first and secondcase bodies 1A and 1B can be reduced compared with the case where thereinforcing frame 6 is molded to be fixed to the case element 5, and thepositioning accuracy between the case element 5 and the reinforcingframe 6 also is enhanced.

In a thin battery in which the mounting region Z is provided on theouter surface of the connection walls 8, 18 of the first case body 1Aand the second case body 1B, the control module 3 and the cover 4 onlyneed to be incorporated successively into the mounting region Z exposedto the outer surface of the outer case 1. Therefore, the assemblyoperation of the control module 3 and the cover 4 with respect to theouter case 1 can be performed easily and exactly. By adding the controlmodule 3 and the cover 4, the thickness of the card-shaped thin batteryis not increased, and the entire battery provided with this type ofcontrol circuit can be miniaturized. Since all the electrical componentssuch as a protection circuit are integrated to form one control module3, the labor for connecting the control module 3 to the battery module 2can be saved. The outer surface of the control module 3 is covered withthe cover 4, so that the adhesion of foreign matter to the mountingcomponents of the control module 3, and inconvenience such as ashort-circuit can be prevented exactly.

In a thin battery in which the positive tab 2 p and the negative tab 2 mof the battery module 2 are led to the mounting region Z, and a pair ofinput terminals 21 p and 21 m of the control module 3 are connected tobe fixed to the tabs 2 p and 2 m, whereby the control module 3 is fixedto the mounting region Z, the control module 3 can be incorporated tothe battery with minimum labor only for mounting the control module 3 ata predetermined position and connecting the input terminals 2 p and 21m. Furthermore, an assembly operation can be performed while confirmingthat an assembled battery is in a state according to the specifications,and further confirming that the control module 3 is normal. Therefore,defective products can be minimized at the completion of assembly.

In a battery in which the cover 4 is composed of the principal planewall 23 covering the outer surface of the control module 3 and a pair ofleg chips 24 projecting from both side ends of the principal plane wall23, and the terminal windows 25 for exposing the output terminals 20 ofthe control module 3 are opened to the principal plane wall 23, a regionof the control module 3 other than the output terminals 20 is coveredwith the cover 4 completely, and the control module 3 can be protectedexactly. The principal plane wall 23 and a pair of leg chips 24cooperate to oppose to the outer force. Therefore, for example, thecover 4 can be prevented from being separated from the battery due todrop impact.

Furthermore, another example of the thin battery of the presentinvention will be described with reference to FIGS. 10 to 12. In thepresent embodiment, concave portions 42 for preventing reverse insertionare formed in side portions of an outer case, and the concave portions42 for preventing reverse insertion are configured so as to be engagedwith convex portions 46 for preventing reverse insertion provided in abattery insertion portion 45 of an apparatus 44 in which a thin battery41 is to be mounted. This can prevent erroneous insertion such asreverse insertion when the thin battery 41 is inserted to the apparatus44.

Furthermore, in the present embodiment, in a side portion of the outercase, a concave portion 43 for preventing dropping is formed so as to beengaged with a convex portion 47 for preventing dropping of a droppingpreventing machine 48 provided in the apparatus 44 in which the thinbattery 41 is to be mounted. Because of this, even when strong impact isapplied to the apparatus 44 in which the thin battery 41 is inserted andmounted, the thin battery 41 does not drop easily.

Next, the present invention will be described by way of an example.

FIGS. 1 to 7 show an example of a thin battery according to the presentinvention. In FIGS. 2 and 3, the thin battery is composed of an outercase 1, a battery module 2 and an electrolyte sealed in the outer case1, and a control module 3 and a cover 4 incorporated to an outer surfaceside of the outer case 1. The outer case 1 is composed of a first casebody 1A and a second case body 1B connected in a lid-fitting manner.

In FIG. 4, the first case body 1A is composed of a case element 5 madeof a press-formed product, and a reinforcing frame 6 fixed along anouter circumferential edge of the case element 5. In FIG. 4, in order toclarify the structural relationship between the case element 5 and thereinforcing frame 6, they are shown as being disassembled.

The case element 5 is made of an aluminum thin plate (thickness: about0.1 to 0.2 mm). A housing portion 7 in a vertically long rectangularshape swells from one surface of the case element 5, and a connectionwall 8 projects in a rectangular dish shape from an outer circumferenceof the housing portion 7. The connection wall 8 is formed narrow onright and left sides and a lower side of the housing portion 7, and isformed wide on an upper side thereof. This is because most of the upperside portion of the connection wall 8 formed wide is used as a mountingregion Z for the control module 3. At right and left two portions on anupper side of the mounting region Z, electrode leading ports 9 are to beopened in a later step.

The reinforcing frame 6 is made of a plastic molding in a rectangularframe shape, and is arranged along an outer circumference of the tiltedswelling wall 11 of the housing portion 7 to be fixed to an outersurface of the connection wall 8 of the case element 5. In the presentexample, the case element 5 is inserted in a mold during injectionmolding of the reinforcing frame 6 to be integrated with the connectionwall 8. When the case element 5 is inserted to be fixed to thereinforcing frame 6, labor for attaching the reinforcing frame 6 to thecase element 5 can be saved, so that the production steps of the batterycan be reduced accordingly. In order to prevent the thickness of thebattery from increasing, the thickness of the reinforcing frame 6 is setto be the same as that of the swelling size of the housing portion 7, asshown in FIG. 1, and the outer surface of the reinforcing frame 6 isflush with the outer surface of the housing portion 7. On both sides ofan upper end of the reinforcing frame 6, connection sections 12 forattaching a cover 4 are formed in a concave shape (see FIG. 4).

A horizontally oriented receiving frame 14 is provided above thereinforcing frame 6 so as to be placed along an upper edge of themounting region Z. The receiving frame 14 is formed simultaneously withthe reinforcing frame 6 to be fixed to the mounting region Z. In FIGS. 4and 5, connection sections 15 for fixing a positive tab 2 p and anegative tab 2 m of the battery module 2 described later are formed onboth lower sides of the receiving frame 14, and an opening 16corresponding to the electrode leading port 9 is formed in eachconnection section 15. Connection sections 17 for attaching a cover 4 ina manner described later are formed respectively on the receiving frame14 and an upper frame portion of the reinforcing frame 6 (see FIG. 4).

In FIG. 3, the second case body 1B is made of a lid in a plate shapeobtained by punching an aluminum thin plate into the same outer shape asthat of the first case body 1A, and by attaching a connection wall 18 onan outer circumferential edge of the second case body 1B to theconnection wall 8 of the first case body 1A, the housing portion 7 canbe closed. In order to set the connection strength between theconnection walls 8 and 18 to be sufficient, and enhance the sealingdegree of the connection surface, a thermoplastic connection resin 27 isbonded to at least one of the connection walls 8 and 18 beforeconnection between the connection walls 8 and 18.

The battery module 2 is configured by winding a sheet-shaped positiveelectrode containing LiCoO₂ as an active material and a sheet-shapednegative electrode containing graphite as an active material in a spiralshape with a separator interposed therebetween, and deforming the woundstructure in an oval shape in cross-section by pressing. The positivetab 2 p and the negative tab 2 m are led respectively at winding ends ofthe positive electrode and the negative electrode, as shown in FIG. 2.

In FIG. 5, the control module 3 has a configuration in which aprotection circuit composed of an IC chip, a switch for disconnecting acircuit, and the like, a polyswitch, etc. are mounted on a reversesurface of a substrate 19, and three output terminals 20 are placed atthe center of a front surface of the substrate 19. The protectioncircuit prevents the battery from being in an overcharging state or anoverdischarging state, and the polyswitch prevents a large current fromflowing to cause thermal destruction. The output terminals 20 arecomposed of a positive output terminal 20 p and a negative outputterminal 20 m positioned on right and left sides and a signal outputterminal 20 s at the center. Input terminals 21 p and 21 m to beconnected to the positive tab 2 p and the negative tab 2 m of thebattery module 2 are fixed to the right and left sides of the substrate19. The signal output terminal 20 s is provided so as to be used, forexample, for detecting the resistance of an ID resistor incorporatedinto the substrate 19 together with the protection circuit anddetermining whether or not the battery is appropriate on the electronicequipment side.

In FIG. 5, the cover 4 is made of a plastic molding in a gate shapeobtained by integrally molding a principal plane wall 23 covering theouter surface of the control module 3 and a pair of leg chips 24projecting downward from right and left sides of the principal planewall 23. Three terminal windows 25 for exposing the output terminals 20(20 p, 20 m, 20 s) of the control module 3 are opened on the right andleft sides and at the center of the principal plane wall 23. Block plugs26 for dosing gaps between the receiving frame 14 and the reinforcingframe 6 project from right and left sides of the reverse surface of theprincipal plane wall 23.

The summary of an assembly procedure of the battery will be described.First, the battery module 2 is mounted in the housing portion 7 of thefirst case body 1A. The positive and negative tabs 2 p and 2 m areinserted into the electrode leading ports 9 and the openings 16.Thereafter, as shown in FIG. 7, the positive and negative tabs 2 p and 2m are bent to be inverted, and exposed to the outer surfaces of theconnection sections 15. At this time, in order to prevent the positiveand negative tabs 2 p and 2 m from coming into direct contact with theelectrode leading ports 9, the tabs 2 p and 2 m are covered with aninsulating tape at some midpoint.

Next, the housing portion 7 is filled with an electrolyte (non-aqueouselectrolyte). Under this condition, the second case body 1B is connectedto the first case body 1A in a lid-fitting manner, and the connectionwalls 8 and 18 of the first case body 1A and the second case body 1B arepressed with heating, whereby the connection resin 27 is melted andthen, solidified. Thus, the battery module 2 is sealed in the outer case1.

The control module 3 is mounted in a blank battery obtained as describedabove, and the cover 4 is fixed thereto, whereby a thin battery iscompleted. More specifically, the input terminals 21 p and 21 m of thecontrol module 3 are overlapped with the positive and negative tabs 2 pand 2 m bent to be inverted to the connection sections 15, and aresubjected to spot welding, whereby the control module 3 is connected tothe battery module 2 electrically. In this state, the control module 3is positioned in a space between the reinforcing frame 6 and thereceiving frame 14 to be housed therein, and the vertical and horizontalfloating of the control module 3 is restricted.

Finally, the cover 4 is placed on the mounting region Z, and thevertical movement of the principal plane wall 23 is restricted by theconnection sections 17 of the reinforcing frame 6 and the receivingframe 17, as shown in FIG. 6. Furthermore, the right and left leg chips24 are engaged with the connection sections 12 (see FIG. 2). Under thiscondition, the principal plane wall 23 and the leg chips 24 areultrasonically welded to the receiving frame 14 and the reinforcingframe 6, whereby the cover 4 is fixed. In this state, the control module3 is interposed between the principal plane wall 23 and the connectionwall 8 in the front and back directions, and only the output terminals20 (20 p, 20 m, 20 s) are exposed to the outside of the cover from theterminal windows 25 (see FIG. 6). Furthermore, both side ends of themounting region Z between the receiving frame 14 and the reinforcingframe 6 are closed with the block plugs 26 provided at the cover 4.

The total thickness of the completed thin battery is equal to the totalthickness of the first and second case bodies 1A and 1B, and the totalthickness in the mounting region Z also is equal to the total thicknessof the completed thin battery. The size of the outer shape of the thinbattery in this example is 90×54×2.5 mm (height×length×thickness). Theoutput voltage thereof is 3.8 V, and the battery capacity thereof is1000 mAH.

In the above-mentioned example, the housing portion 7 is provided onlyin the first case body 1A. However, as shown in FIG. 8, the housingportion 7 also may be provided in the second case body 1B, and thereinforcing frame 6 also may be attached to the outer circumferencethereof.

In addition to the above, the following also can be performed. Thereinforcing frame 6 is molded previously, and bonded or welded to befixed to the connection wall 8. The outer shape of the outer case 1 isnot required to be a rectangle, and can be varied into an arbitraryshape depending upon the configuration and shape of electronic equipmentto which the battery is applied. The first case body 1A and the secondcase body 1B may be formed of a stainless thin plate or a plated thinsteel plate, and can be fixed by bonding with an adhesive or seamwelding. The first case body 1A and the second case body 1B may be madeof different materials. The mounting region Z can be provided at aplurality of portions of the outer circumference of the outer case 1.The receiving frame 14 may be integrally molded with the reinforcingframe 6. The cover 4 can be integrally molded with the receiving frame14 via an integrally molded hinge. The thin battery of the presentinvention also is applicable to batteries other than a lithium ionbattery.

Furthermore, FIGS. 10 to 12 show another example of the thin batteryaccording to the present invention. In the present example, concaveportions 42 for preventing reverse insertion further are formed on sidesof the outer case, and the concave portions 42 for preventing reverseinsertion are to be engaged with convex portions 46 for preventingreverse insertion provided in a battery insertion portion 45 of anapparatus 44.

Furthermore, in the present example, a concave portion 43 for preventingdropping further is formed on a side of the outer case, and the concaveportion 43 for preventing dropping are to be engaged with a convexportion 47 for preventing dropping of a dropping preventing machine 48provided in the apparatus 44 in which the thin battery 41 is to bemounted.

INDUSTRIAL APPLICABILITY

The present invention can provide a thin battery that has sufficientstructural strength while the total thickness of the battery isminimized, and that is preferable as a power source of a portalinformation terminal or the like strictly required to be light-weightand miniaturized.

1. A thin battery comprising a battery module and an outer case forhousing the battery module, wherein the outer case includes a first casebody and a second case body, the first case body and the second casebody include connection walls for connecting the first case body and thesecond case body to each other on outer circumferential portions, atleast one selected from the first case body and the second case bodyincludes a dish-shaped case element with a housing portion swelling fromone surface and a reinforcing frame fixed to the case element along acircumference of a swelling wall of the housing portion, the batterymodule is housed in the housing portion, and the battery module issealed in the outer case by attaching the connection wall of the firstcase body to the connection wall of the second case body.
 2. The thinbattery according to claim 1, wherein the reinforcing frame is made of aplastic molding, the case element is a press-formed product made of ametal thin plate, and the case element is formed so as to be integratedwith the reinforcing frame.
 3. The thin battery according to claim 1,wherein a mounting region further is formed on an outer surface of theconnection wall adjacent to the swelling wall of the housing portion,and the mounting region includes a control module for the battery moduleand a cover for protecting the control module.
 4. The thin batteryaccording to claim 3, wherein the control module includes a protectioncircuit, output terminals and input terminals, and a pair of the inputterminals of the control module are connected to be fixed to a positivetab and a negative tab of the battery module led to the mounting region,whereby the control module is fixed to the mounting region.
 5. The thinbattery according to claim 3, wherein the outer case is formed in arectangular card shape, the mounting region is provided on one side ofthe outer case, the cover includes a principal plane wall covering anouter surface of the control module and a pair of leg chips projectingfrom both ends of the principal plane wall, and terminal windows forexposing the output terminals of the control module are opened in theprincipal plane wall.
 6. The thin battery according to claim 1, whereina concave portion for preventing reverse insertion further is formed onone side of the outer case, and the concave portion is engaged with aconvex portion for preventing reverse insertion provided in a batteryinsertion portion of an apparatus in which the battery is to be mounted.7. The thin battery according to claim 1, wherein a concave portion forpreventing dropping further is formed on one side of the outer case, andthe concave portion is engaged with the convex portion for preventingdropping provided in an apparatus in which the battery is to be mounted.